﻿<p>A zone is a group of spaces,
partial spaces or other zones. Zone structures may not be
hierarchical (in contrary to the spatial structure of a project -
see <em>IfcSpatialStructureElement</em>), i.e. one individual
<em>IfcSpace</em> may be associated with zero, one, or several
<em>IfcZone</em>'s. <em>IfcSpace</em>'s are grouped into an
<em>IfcZone</em> by using the objectified relationship
<em>IfcRelAssignsToGroup</em> as specified at the supertype
<em>IfcGroup</em>.</p>

<blockquote class="note">
NOTE&nbsp; Certain use cases may restrict the
freedom of non hierarchical relationships. In some building
service use cases the zone denotes a view based delimited volume
for the purpose of analysis and calculation. This type of zone
cannot overlap with respect to that analysis, but may overlap
otherwise.
</blockquote>

<blockquote class="history">
HISTORY&nbsp; New entity in IFC1.0
</blockquote>

<blockquote class="change-ifc2x4">
IFC4 CHANGE&nbsp; The entity is now subtyped from <em>IfcSystem</em> (not its supertype <em>IfcGroup</em>) with upward compatibility for file based
exchange.
</blockquote>
